Thumbs.db file is generated by virus in most of my folders of the computer. How to clean the virus. Please help me in this regard. I have cleaned my computer with Mcafee anti virus but this has not helped. Please advice.

Hi
My PC has been hit by tazebama and shows the below symptoms:
1- loggs of in a few seconds after logging on.
2- can't seem to load in safe mode as an error screen is shown .
How can I boot in safe mode and upgrade xp or how do I stop the virus from logging off.